I. Field of the Invention
The present invention relates to processes, apparatus, and compositions for the enhancement of hydrocarbon conversion processes, particularly processes involving the contacting of hydrocarbon feeds with particulates such as catalyst and sorbents, especially fluid catalytic cracking processes. The RCC.RTM. heavy oil cracking process, generally classified in U.S. Patent Class 208, International Patent Classification C10G11.
II. Description of the Prior Art
In an FCC process, metals accumulate onto the catalyst, the catalyst becomes deactivated with time and in order to maintain FCC unit activity, a fraction of the unit inventory is withdrawn and fresh catalyst is added. The spent catalyst (withdrawn catalyst) contains a dynamic mixture of catalyst particles from very old/high metals, low activity to newer/low metals high activity. In order to produce a separation using magnetic separation techniques, the catalyst must exhibit magnetic properties, notably magnetic susceptibility. As metals are deposited onto the catalyst particles over a period of time, the magnetic susceptibility of those catalyst particles increases, FIG. 2, and magnetic separation can be achieved with the MagnaCat.RTM. Process. When antimony (Sb) is added to a FCC process unit, it is laid down onto the catalyst particles and reacts with the metals present (notably iron) on the particle. It has been demonstrated that, with the addition of antimony, the magnetic susceptibility of these catalyst particles increase and an enhanced magnetic separation can be obtained. The antimony can also be used as a tag for determination of age distribution of said catalyst.
Antimony has frequently been added to cracking catalyst to "passivate" the catalyst and reduce the production of hydrogen and other undesirable light gaseous products, e.g., in U.S. Pat. No. 4,459,366, U.S. Pat. No. 4,457,693, U.S. Pat. No. 3,711,422, and U.S. Pat. No. 4,334,979.
Magnetic separation has been taught by a number of U.S. patents such as U.S. Pat. No. 4,406,773, U.S. Pat. No. 5,147,527, U.S. Pat. No. 5,106,486, U.S. Pat. No. 5,171,424, and U.S. Pat. No. 5,230,869 to Hettinger et al., which teaches the removal of inactive catalyst and sorbents from mixtures of active and inactive particulates so that the active particulates can be recovered for reuse.
However, it has not been previously taught that the passivating advantage of antimony on conversion on catalyst and sorbents can be coupled with the enhanced magnetic susceptible of metals such as iron in the presence of antimony to obtain the advantages of passivation and selective recovery of more active particulate.